Methods of Protein Digestive Stability Assay - State of the Art

IntroductionThe evaluation of protein stability in digestive tract is an important topic in various fields of biomedical sciences.The most straightforward task within it is the evaluation of food quality, as during the food processing the digestibility of a protein could fall dramatically.Another task, tightly connected with the previous one, is the evaluation of protein allergenicity.This parameter is shown to be dependent on protein's digestibility, the less digestible ones having the highest probability to induce immune response.Finally, the task of development of new peptide drugs also requires digestive stability check for per os drug forms that are the most convenient for a patient.Current knowledge on protein digestion suggests it to be a multistage process, starting from pepsin cleavage in stomach and proceeding through trypsin and chymotrypsin digestion in intestinal lumen, and finally involving cleavage by intestinal surface and intracellular proteases.The latter two protease groups accomplish the most deep protein degradation.An intriguing point is that in spite of this knowledge the models, which include all stages of protein digestion, are used primarily in food quality control.Protein digestion, specific enzymes, involved in this process, as well as research area specific methodology for protein digestibility evaluation is regularly reviewed.However, as a common rule, the authors of latter group of reviews ignore the existence of methods with similar goals in other research areas, as well as the question of a degree to which any given method represents a living organism.The aim of this review is to describe existing models for evaluation of protein digestibility with a special emphasis on biological relevance provided by distinct model as well as on productivity of each methodology. Protein and peptide digestionBefore a discussion of protein digestibility evaluation methods, it seems worthwhile to introduce a reader to the current understanding of protein and peptide digestion process in order to provide him with a holistic picture of what could happen to an ingested protein.That is why this section will give a short description of digestive tract and an evaluation of enzymes involved in protein digestion in stomach and intestine.A special emphasis will be laid on characterization of intestinal wall peptidases (surface as well as intracellular) with description of their specificities and their role in overall protein digestion.www.intechopen.